1. Field of the Invention
The present invention is directed to a bright wire draw process and apparatus. The process and apparatus include treatments of stock after pressure die drawing which include pre-die enhanced lubrication and post-die buffing. Higher speeds and more efficient production is achieved.
2. Prior Art Statement
The commerce of bright wire production has been active for decades and the end use of bright wire is very diverse. Metal hangers, nails, medical devices, axles, pins, shafts, rods, hooks, etc., are fabricated from bright wire, to name a few. The broad based market for bright wire includes carbon steel, alloy steel and stainless steel, as well as others.
Historically, metal stock, sometimes called hot rolled wire or rod, is manufactured from molten metal and subsequently reworked or sold for reworking into different sizes (and shapes) These stock rolls have been stretched or drawn into lesser diameters, for example, through pressure dies, and have been pretreated to remove scale or oxides, and have been lubricated to prevent rapid wear of the dies. Typically, pretreatment for scale removal involved the use of acid baths, and, even today, production facilities may utilize a batch type pickling process for descaling whereby cranes or hoists physically dip rolls of stock into and out of large heated vats of acid and rinse water and dryers. This descaling operation is costly due to labor needs, it requires large floor space and expensive equipment is slow, creates long down times for bath changes and may cause pollution problems such as spent acid disposal and acid evaporation.
Some of the very modern facilities for drawing bright wire utilize continuous instead of batch processes, but the wire must be traversed back and forth over pulleys in the baths to provide adequate bath and rinse times. Further, spent acid, evaporation, floor space and other problems remain even though the batch method is supplanted by continuous flow methods.
Additionally, bright wire production is achieved by the descaling, drawing and brightening of the wire product. This brightening is accomplished by control of limited or no lubrication to the wire as it passes through its final draw (smallest, last die). The friction of the die scrapes or otherwise removes any coatings and yields a bright product. While this method is acceptable industry wide, it does cause wear and frequent replacement of the final die and requires substantial power to pull the stock through the die by overcoming the intentional frictional drag.
These problems stated have not been addressed or overcome by the industry or prior art until the present invention. For example, good continuous draw technology which in many respects may be today's standard, is exemplified by the 1923 patent to Ernst Boley as U.S. Pat. No. 1,470,374. This patent describes the state of the art, except for perhaps computerized or modern speed control systems, but these are not the subject of the present invention. In the Boley method, three or four baths are utilized, including an acid bath and the problems pertaining thereto as discussed above are not eliminated.
To minimize problems of wire resting in acid baths during down time, e.g. die changes, etc., the art teaches the use of an intermediate wire collecting and feeding device as shown in U.S. Pat. No. 3,354,687 to Walter Mauson. While this patent issued more than 40 years after Boley, it confirms the continuing use of acid baths for descaling.
It is believed that the prior art does not address the problem of die wear and has not taught nor suggested the present method and apparatus.